The royal commission into abuse in the Northern Territory juvenile justice system will focus on why investigations highlighting problems in the system were not sufficiently followed up, and whether detention centres have breached human rights obligations.

Federal cabinet agreed on the royal commission's terms of reference today, with former Northern Territory chief justice Brian Martin named to head the inquiry.

When pressed on the role race or racism may play in the royal commission, Mr Martin said the terms of reference included "questions about the culture within the system".

"Naturally, if people believe that racism plays a role, then that will be a subject of evidence before the royal commission," he said.

Attorney-General George Brandis said the royal commission would primarily examine "failings in the child protection and youth detention systems administered by the Government of the Northern Territory".

"We've asked him to inquire into whether there are, or were, any deficiencies of the organisational culture, structure and management in the Northern Territory's youth detention facilities," he said.

Senator Brandis said the royal commission would examine the period since the Northern Territory Youth Justice Act came into operation in 2006.

He said there would also be a focus on why two reports into the youth justice system — including one relating to the Don Dale centre — were not sufficiently followed up.

Senator Scullion, who is the only Northern Territory Coalition Senator and has held the portfolio since September 2013, said he was not aware of allegations of abuse within the Northern Territory juvenile detention system, because they had not "piqued his interest".

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